At the time of initiation of rounds of chromosome replication in E. coli B/r, phosphatidylethanolamine, the stable component of the membrane phospholipid increases its rate of synthesis abruptly. The stepwise increase in rate of phosphatidylethanolamine during the cell division cycle, coincident with chromosome initiation, had suggested that in a cell new sites of envelope growth are inaugurated at the time new rounds of chromosome replication are initiated. The objective of the proposed research is to determine whether other elements of the envelope, namely the peptidoglycan layer and membrane and wall proteins increase their rate of synthesis concomittant with the increase in rate of phosphatidylethanolamine, consistent with the activation of new growth sites at a given time in the cycle. We also wish to determine whether specific signals for termination of synthesis at a given growth site or for cell division are expressed during the cell division cycle through changes in the degree of binding of newly synthesized murein strands and lipoprotein to the peptidoglycan layer and in the turnover of preexisting molecules. The extent of coupling between envelope growth and chromosome replication will be investigated. The study will include the analysis during the cell of E. coli B/r A, F and K and possibly of E. coli K12 of 1) the pattern of synthesis of phospholipids, murein and envelope proteins, 2) the pattern of turnover of phospholipids murein and envelope proteins, 3) the determination of the sizes of the cells at a variety of growth rates and temperature of incubation. The study will be performed in cultures growing under conditions of balanced growth and, with particular emphasis, in slowly growing cultures since the timing of initiation and termination of rounds of chromosome replication during the cycle are best defined at the slow growth. The pattern of synthesis and turnover of envelope components during the transitions between defined balanced growth conditions and growth temperatures will be analyzed.